Supersonic commercial jet flights to make a comeback? Not so fast!
PIE IN THE SKY? Researchers try to figure out how to silence ‘sonic boom,’ but many hurdles remain
Just when you thought it safe to go back on a plane comes news that researchers are again trying to figure out how to fly faster than the speed of sound – without the sonic boom!
At least five companies – including one partnered with NASA – have plans to develop and build commercial Supersonic Transports (SSTs) similar to Concorde, which stopped flying almost 20 years ago.
But, before you jump aboard, beware: There are huge, unanswered questions about the feasibility, economic viability and climate effects – quite apart from whether they can address the most daunting challenge of all: the sonic boom!
Although it’s a fascinating prospect, a healthy dose of skepticism is definitely advisable.
Of all the difficult issues surrounding commercial SST flights, the sonic boom is a physical manifestation that has proven extremely difficult to crack. When an aircraft travels faster than the speed of sound – about 768 mph at sea level – it sets up a shockwave that reverberates outwards resulting in a loud double bang.
The Federal Aviation Administration tested the impact of that big bang in 1964 by flying military supersonic jets over Oklahoma City for six months. The result: damaged buildings, collapsed walls and ceilings, frayed nerves and public outrage.
It was obvious that no one was going to tolerate such a loud noise on a continuing basis.
The result was a ban on civilian supersonic flights everywhere in the world other than over open water.
Since then, the speed of commercial jetliners has actually declined and they average less than 600 mph today.
The new SST project that is most advanced – and the one most likely to succeed because it is taking on the most difficult problem first – is a collaboration between defense contractor Lockheed Martin Corp. and NASA.
The project is under way at Lockheed Skunk Works where you can see the range of defense projects the company has been involved in, including its work on supersonic aircraft (mostly for military applications):
“We are proud to support the DoD and warfighters in developing rapid and cost effective hypersonic solutions. Our robust experience in high-speed flight is the foundation on which we are developing cutting edge technologies to enable hypersonic solutions,” its website says.
Essentially, it has a credible and long track record in making supersonic aircraft – something the other contenders in the race for a new commercial SST conspicuously do not have.
Its project for a new supersonic aircraft – called the X59 QueSST (Quiet SuperSonic Technology) – was first commissioned by NASA in February 2016, according to the website LockheedMartin/NASA X59 QueSST
In 2018, Skunk Works was given a contract for the design, building and flight testing phase of the project.
“In partnership with NASA, the Lockheed Martin Skunk Works team is solving one of the most persistent challenges of supersonic flight – the sonic boom,” says the firm on its web site.
The design of the aircraft is the most crucial part of solving the problem. A report on its research was released in June 2019, and design review completed in September 2019.
Lockheed in now building the first prototype of the X59 at the Skunk Works Assembly Building in the Los Angeles area, and recently took Bill Whittaker of the CBS 60 Minutes show on a tour of the facility broadcast.
The first thing one notices from artists’ renderings of the finished aircraft is its unusual shape: It resembles a long pencil more than a conventional plane in that the elongated surfaces are all super-smooth with virtually no protrusions at all.
What an observer cannot miss is, actually, what’s missing: There is no cockpit windshield for the pilot to look out of!
“Every part of the X59 is streamlined and smooth to disperse sound waves and transform the loud sonic boom into a much quieter thump,” Whittaker explains.
Dave Richardson of Lockheed Martin says: “You're looking at the cockpit of the airplane, and there's no forward windscreen.”
NASA test pilot Nils Larson adds: “If you look at it, it's pretty slick. It looks like a dart.”
In a simulator we discover how Larson (and future pilots) will fly the plane: Instead of the windshield, there is a video screen facing the pilot.
Larson says that works just as well – if not better – than being able to look out of the forward-facing windows normally seen on the cockpit of conventional aircraft.
It is perhaps the most surprising feature of the X59, but intuitively it makes sense if the goal is to minimize the waves of disturbances that contribute to the sonic boom.
Larson is scheduled to begin test flights of the X59 next year, and then test it at speeds faster than Mach 1 (the speed of sound) to see what it sounds like.
“It’s coming to a town near you,” he says, confidently. “So our researchers are going to work with the public and we're going to fly over various cities and towns and they're going to give us the feedback on that thump. Was that thump too loud? Did you even hear it at all?”
Based on the public reaction, if it is positive the FAA will be asked to allow it to fly over populated areas on a routine basis.
On it’s web site, this part of the project is further explained:
“X-59 QueSST will be used to collect community response data on the acceptability of a quiet sonic boom generated by the unique design of the aircraft. The data will help NASA provide regulators with the information needed to establish an acceptable commercial supersonic noise standard to lift the ban on commercial supersonic travel over land.”
If it works, “this breakthrough would open the door to an entirely new global market for aircraft manufacturers, enabling passengers to travel anywhere in the world in half the time it takes today.”
When might it be able to start passenger service?
“There's a long line of things that have to happen starting with the X59,” Richardson says. “But I think 2035 is the answer, if everything marches along the way that it's supposed to.”
The real test will come sometime next year when the X59 first breaks the sound barrier.
“And when we hear – or don't hear – that sound is when we know we did it,” Richardson says.
Another contender in the race for a new commercial SST is the XB1 Overture from BOOM Technology which bills itself as “History’s first independently developed supersonic jet.”
“XB-1 is paving the way for mainstream supersonic travel by demonstrating the key technologies for safe and efficient high-speed flight,” it says
Its aircraft is called the “Overture” which promises “flights twice as fast [to] enable us to experience more people, places, and cultures.”
So far the XB-1 exists only in artists’ renderings, but they are sufficient to have convinced one of the largest airlines.
Speaking to CBS, BOOM founder and CEO Blake Scholl says: “United just ordered 15 Overture airplanes, [so] it's incredibly validating. When you are United, you take these things really seriously.”
Seriously? Perhaps, but this raises an interesting (and unanswered) question: Why name your company with the single word that would be most discouraging to any purchaser … or, for that matter, any passenger? BOOM (all capitals, no less) seems like an unlikely selling point for a new generation SST which must do everything possible to avoid a “boom.”
Scholl is a software engineer, but he insists he's going to make Overture happen.
“When I look several decades out, you know, what I want is to be able to be anywhere in the world in four hours for $100. Now that's not where we start, but that's the end goal.”
It’s a very ambitious goal. The Concorde had to charge over $6,000 for a one-way ticket from New York to London.
Scholl says his firm will keep developing its prototype until they get it right.
“So we're doing [numerous iterations] with supersonic jets. We're gonna keep working on them, keep innovating.”
While Scholl is clearly an optimist, when it comes to the nuts and bolts, he is also a realist. He estimates his SST will cost $7 to $8 billion to develop, and so far he has raised $300 million. He promises his new plane will use “sustainable” fuel … which doesn’t yet exist in any quantities sufficient for his needs.
And, BOOM is going to need an engine for its aircraft, another thing that doesn’t yet exist. “We are working with Rolls Royce on a custom jet engine that will power Overture,” Scholl says.
He hopes to have his first paying customers by the end of the decade. “The airplanes we have today are no faster than the ones we had when my parents were growing up,” he says. “And there is no good reason for that. It doesn't have to be. We can fix it.”
If all it would take is passion and optimism, then Scholl may have a point.
But the technical hurdles remain enormous, the amounts of money required vast – and few except perhaps NASA seem close to resolving the issue of the sonic boom.
Another entrant in the race for a new SST is Spike Aerospace which says on its web site: “Spike Aerospace, Inc. is leading a global collaboration of world-class aerospace firms in development of the world’s first quiet supersonic jet, the Spike S-512.
“This revolutionary luxury aircraft, with proprietary Quiet Supersonic Flight technology, will cut flight times in half.”
But there are few details about just how it will accomplish that. In fact, after eight years it would appear to be still in the design phase:
“Since 2013, Spike Aerospace has been designing and engineering the Spike S-512 Supersonic Business Jet. We have spent thousands of hours studying various configurations and optimizing the aircraft’s performance to meet the needs of very demanding customers and regulators.
“Design continues to be improved upon as we learn from further analysis and our first prototypes.”
Like the others in the field, Spike will also face daunting obstacles. It does not in any detail appear to address the issues of engine development, fuel, costs and how it will raise capital or mitigate climate changing emissions.
Spike seems to be much further behind in the race.
Where is the demand?
All of this raises a fundamental issue which none of the companies have addressed in any meaningful way: Is there really sufficient demand for supersonic flight that can realistically be met with competitively priced service that does not massively contribute to climate changing emissions?
This is the billion dollar question – that does not seem to have an answer at this time.
While NASA and Lockheed Martin may be on the cusp of solving some of the technical problems, the economic and environmental ones still need to be addressed. They are huge.
While the concept stimulates the imagination and optimism of insiders and SST buffs, a healthy dose of skepticism should come along with it to keep the rest of us grounded in reality.